Cathode ray tube having image-forming elements in displaced,parallel planes



Nov. 11, 1969 D. CICCOTTO 3,473,242

CATHODE RAY TUBE HAVING IMAGE-FORMING ELEMENTS IN DISPLACED, PARALLEL PLANES Filed May 15, 1966 FIG INVENTOR DOMENICK ICCOTTO BY ATTORNEY United States Patent 3,478,242 CATHODE RAY TUBE HAVING IMAGE-FORMING ELEMENTS IN DISPLACED, PARALLEL PLANES Domenick Ciccotto, 527 Ovington Ave., Brooklyn, N.Y. 11209 Filed May 13, 1966, Ser. No. 549,897 Int. Cl. H01j 29/18 US. Cl. 313-92 2 Claims ABSTRACT OF THE DISCLOSURE The present inveniton relates to three-dimensional television. More particularly, it relates to a cathode tube adapted to produce a three-dimensional image and .to a method for transmitting a three-dimensional image.

Cathode ray tubes adapted to produce both black and white and color television images are well known. Such tubes, however, are capable of producing only a Z-dimensional image on a surface. The provision of means for producing a 3-dimensional image, that is, one having depth as well as height and width, would be a notable advance in the art and be extremely advantageous in educational and instructional programming.

It is, accordingly, an object of the present invention to provide a cathode tube adapted to produce a 3-dimensional image. Another object is to produce a 3-dimensional image with a cathode tube having a single electron gun. A further object is to provide a cathode tube capable of producing a 3-dimensional picture which can also be used in conventional Z-dimensional television. Another object is to provide a cathode tube capable of producing a 3-dimensional picture in color or black and white with a single electron gun. Still another object is to provide means for transmitting a 3-dimensional image. These and other objects of the present invention will become apparent from the following description.

It has now been found that a 3-dimensional image may be obtained by a cathode tube comprising two separated parallel image receiving screens, each screen containing fluorescent elements arranged in horizontal lines, the lines in each screen being staggered relative to one another.

Each of the screens of the cathode tube of the present invention is similar to the screen of conventional television viewing tubes, but differs in having fewer fluorescent elements. In conventional black and white television, the fluorescent elements of the viewing screen may be arranged in a maximum of 525 parallel equidistant lines, an image being formed when electrons emitted from the electron gun scan the screen from top to bottom. This scanning takes place in two successive steps, alternate lines being omitted in each step. In the first step the first line and every alternate line beginning with the first, that is, all the odd lines, are scanned while in the second step the second, and every alternate line beginning therewith, that is, all the even lines, are scanned. When operating at a conventional frequency of 15,750 cycles per second, the 525 lines are scanned 30 times per second, or expressed otherwise, it takes A second to scan the 525 lines. As the scanning takes place in two steps, it will be apparent that a single scanning of all 525 lines taking second consists of two successive partial scannings, a first "ice scanning of odd lines taking second followed by a second scanning of even lines taking ,4 second. (While 525 lines is the theoretical maximum in conventional black and white television in the United States, it is to be understood that in actual practice, the total amount may be somewhat less.)

In the cathode tube of the present invention, the two separated screens taken together have a total of no more than 525 lines. More exactly, one screen contains approximately 263 lines and the other approximately 262 lines. In effect, therefore, the cathode tube of the present invention comprises a physical separation into two screens of alternate image forming areas of the single screen of conventional television tubes. Generally, the distance between screens should be from about 0.04 inch to about 0.75 inch or more, depending upon the degree of 3-dimensional effect desired. The lines may be formed of any material, e.g., wire, filament, fiber or plastic, capable of being coated with any suitable fluorescent material, e.g., zinc sulfide, which will glow under electron bombardment, and of being arranged in parallel rows.

In conventional television the entire image forming screen may be coated with an opaque fluorescent material. This is not permissible in the cathode tube of the present invention as such an opaque coating would prevent viewers from seeing the image on the inner screen. It is essential, therefore, for 'each screen that (1) the fluorescent lines be arranged in horizontal, parallel rows, the distance between rows being equal, and (2) that two lines of the inner and outer screens be staggered relative to each other so that the electron pattern destined for the front screen may pass through the spaces between the lines of the inner screen.

The I i-dimensional image is transmitted by the alternate use of two conventional transmitting television cameras. That is, while both cameras continuously scan the image to be transmitted, the transmission from each camera is interrupted alternately at a frequency of 6 second. The effect of this alternate interruption is a projection of the image scanned by the first camera to one screen while the image scanned by the second camera is projected to the other screen thereby forming two distinct images. This method will be described below in greater detail.

The invention will appear more clearly from the following detailed description when taken in connection with the accompaying drawing showing, by way of example, preferred embodiments of the inventive idea.

In the drawings:

FIGURE 1 is a plan view of a cathode tube according to the present invention having two image-forming screens.

FIGURE 2 is a front elevation of the image-forming screens showing the staggered relationship of the lines in each screen.

FIGURE 3 is an oblique view of the image-forming screens wherein the lines of fluorescent material are contiuous to both screens.

FIGURE 4 shows the arrangement of cameras for transmitting a 3-dimensional image.

The cathode tube 10 of FIGURE 1 is similar to conventional television tubes in comprising electron gun (having heater 11, emitter 12 and grids 13), and front viewing surface 14. Within tube 10 are outer viewing screen 15 and inner viewing screen 16. Although shown here as a separate member, the outer screen could also be stamped or ruled on the inside of the front surface of the cathode tube. In this case the cathode tube of the present invention would have an inner screen comprising a line forming material and an outer screen comprising lines of fluorescent elements applied directly to the inside of the front of the cathode tube.

FIGURE 2 is a front elevation showing the staggered relationship of the lines (only a few of the actual number of lines being shown for simplicity) in screens and 16 as well as the parallel relationship of the two screens. Screens 15 and 16 are in spaced apart and staggered relationship such that if the two screens were superimposed, the wires of one screen would contact the area between the wires of the other screen. The screens 15 and 16 are formed of a plurality of parallel lines 53-62 coated with fluorescent elements (not shown) in conventional manner and attached to frames 17 and 18, respectively, by any convenient means (not shown), e.g., fastened to slots or notches, wound, tied, etc. Frames 17 and 18 are held in fixed position by slots (not shown) provided in the wall of tube 10. Any other fastening means, e.g., wedges, spacer clips, etc. is equally suitable. The frames 17 and 18 may be of any suitable non-conductive material, e.g., wood, plastic, or glass, having the requisite strength to hold the lines taut in fixed relationship.

Screens 15 and 16 may also be formed of continuous fluorescent elements wound around a single supporting frame in such manner that the fluorescent elements at the front and back of the frame are in staggered relationship. Such an arrangement is shown in FIGURE 3 in which frame 19 is wound with a single continuous fluorescent coated wire 20. Zinc sulfide is a suitable fluorescent material. Any other conventional fluorescent material, however, is suitable. The wires are parallel and equidistant on both front and back surfaces (screens 15 and 16, respectively). As shown in the drawing, the wires are held in place by engaging notches or slots 21 at the edges of the frame 19. In order to achieve a staggered arrangement of the wires in the front and back surfaces of frame 19, the wires pass downwardly in a diagonal direction along the sides of the frame so that the front and rear fluorescent elements are maintained in staggered relationship and never overlap. This staggered relationship permits the electron pattern emitted by electron gun 11 to strike the lines of fluorescent material of inner screen 16 forming an image thereon in one partial scaning and then to pass through the interstices of said screen in the next partial scanning forming an image on outer screen 15. In this manner a single electron gun forms an image on both screens.

The transmission is efifected in conventional manner except that two alternately transmitting cameras are employed. The 3-dimensional effect is determined by the distance between the two cameras and the distance from the cameras to the object. For a given focal length, the 3-dimensional effect is heightened as the distance between the cameras is increased. Preferably, the distance between the two cameras is fixed, for example, by locking the cameras together, to facilitate joint operation of the cameras.

FIGURE 4 shows two transmitting cameras 22 and 23 having a common intersecting focal point A. The cameras are held in fixed relationship relative to one another by connecting rods 24 and 25. Any other suitable fixing means may be employed.

In order to heighten the 3-dimensional effect, instead of having a common focal point, the focal point of each camera may be different. One camera may focus on the foreground (point B in FIGURE 4), while the other camera focuses on the background (point A). (In this case, of course, it is essential that the picture from the camera focusing on the foreground be transmitted to the front viewing screen of the television receiver. The manner of achieving this is described below.) As the distance between the focal point of each camera increases, the 3-dimensional effect is increased. At the same time, however, detail is diminished. As a practical matter, therefore, a balance must be struck between increased 3-dimensional effect and loss of detail. Generally, the distance between focal points may be increased until the loss of detail becomes objectionable.

In 3-dimensional transmitting according to the present invention the cameras transmit alternately so that one camera scans the odd lines for 4 second, and then has its transmission interrupted while the second camera scans the even lines. Both cameras are operating continuously, but the signal from each camera is interrupted alternately. Thus, both cameras scan odd lines for ,4 second, but the signal from the second camera is interrupted during this scanning so that only the first camera tranismits the odd lines scanned. Then while both cameras scan even lines, the signal from the first camera is interrupted so that only the second camera transmits the even lines scanned. The alternate interrupting of the signal from each camera may be accomplished by any conventional mechanical or electronic switches (not shown) operating at a frequency of 60 cycles per second. As examples of such switches, there may be mentioned reed or vibrator switches, or a rotary distributor with alternate connections to each camera.

From the foregoing description it will be seen that the first camera transmits only odd lines scanned and the second camera transmits only even lines scanned. Consequently, if the focal lengths of the two cameras differ, the first camera will always focus on the foreground as the odd lines it scans will be transmitted to the front screen. In practice this is affected simply by projecting a test pattern and exchanging the focal length of each camera if the background image is being transmitted to the outer (foreground) screen.

The projection of a 3-dimensional image by means of the conjoint use of the transmitting method and cathode tube of the present invention will now be described. Television cameras 23 and 22 are activated to scan simultaneously an object for transmission. Because of the alternate interruption of transmission, all image patterns produced on the outer screen, will correspond to the image transmitted by one camera while, correspondingly, all image patterns produced on the inner screen will correspond to the image transmitted by the other camera. The result will be a distinct image produced on each screen thereby producing a 3-dimensional effect.

It will be appreciated that the separated screens must be maintained in correct staggered relationship with respect to each other and also that each screen must be in alignment with the electron gun so that the image will be formed on the proper screen. The alignment may be carried out in various known ways. For example, a weak magnet may be positioned on the neck of the tube to align the electron beam. In another method, the inner screen may be charged negatively in synchronization with the transmission of an electron pattern to the outer screen, thus tending to repel electrons from the lines of the inner screen and inducing them to pass through the spaces between lines of the inner screen.

While the foregoing description is concerned specifically with black and white television transmission, the transmission system and cathode tube may be used equally for color transmission. In such a case, two color television cameras would be used for transmission and the cathode tube screens would each contain a compound line for each of the 525 single lines used in the black and white cathode tube. A compound line composed of three color lines would simply be substituted for each single line, and would occupy the space formerly occupied by each single line.

While the cathode tube of the present invention is particularly adapted for producing a 3-dimensional image, it is to be understood that such tube is also capable of being used in conventional Z-dimensional television. In such case the screens are preferably located closer together.

As the screens of the television tube of the present invention are physically separated, in some cases it may be necessary to alternately apply different voltages to the electron beam depending on the respective screen to which it is directed to keep the beam in focus on the respective screen. This may be accomplished in known manner, for example, by a reed switch or other means connected to a power source and two potentiometers to regulate the proper voltage of the focussing grid in synchronization with the alternately transmitting cameras.

What I claim is:

1. A cathode ray tube having an electron gun, scanning means, and a display screen having image-forming elements in parallel and displaced planes, said display screen comprising a frame substantially parallel to the image-viewing wall of said tube and having means for retaining a phosphor-coated, conductive member wound helically on said frame to form a plurality of substantially horizontal image-forming elements in each of said parallel and displaced planes, said elements in one of said planes being interlaced with respect to the elements in the other of said planes whereby electrons from said gun may scan both said pluralities of image-forming elements.

6 2. A cathode ray tube as in claim 1 wherein said retaining means comprises indentations at the sides of said frame.

References Cited UNITED STATES PATENTS 2,722,623 11/1955 Law 3l392 X 2,861,210 11/1958 Rennick.

3,005,196 10/ 1961 Aiken.

3,284,653 11/1966 De Frances et a1. 313-89 1,866,169 7/1932 Nicolson l78-6.5 2,301,254 11/1942 Carnahan 178-65 2,307,188 1/ 1943 Bedford 1786.5 3,089,917 5/ 1963 Fernicola 1786.5

ROBERT SEGAL, Primary Examiner U.S. c1. X.R. 178-65; 313-348 

